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<h1>fasttimer_isr.c</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*********************************************************************************</span>
<a name="l00002"></a>00002 <span class="comment"></span>
<a name="l00003"></a>00003 <span class="comment"> Copyright 2006 MakingThings</span>
<a name="l00004"></a>00004 <span class="comment"></span>
<a name="l00005"></a>00005 <span class="comment"> Licensed under the Apache License, </span>
<a name="l00006"></a>00006 <span class="comment"> Version 2.0 (the "License"); you may not use this file except in compliance </span>
<a name="l00007"></a>00007 <span class="comment"> with the License. You may obtain a copy of the License at</span>
<a name="l00008"></a>00008 <span class="comment"></span>
<a name="l00009"></a>00009 <span class="comment"> http://www.apache.org/licenses/LICENSE-2.0 </span>
<a name="l00010"></a>00010 <span class="comment"> </span>
<a name="l00011"></a>00011 <span class="comment"> Unless required by applicable law or agreed to in writing, software distributed</span>
<a name="l00012"></a>00012 <span class="comment"> under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR</span>
<a name="l00013"></a>00013 <span class="comment"> CONDITIONS OF ANY KIND, either express or implied. See the License for</span>
<a name="l00014"></a>00014 <span class="comment"> the specific language governing permissions and limitations under the License.</span>
<a name="l00015"></a>00015 <span class="comment"></span>
<a name="l00016"></a>00016 <span class="comment">*********************************************************************************/</span>
<a name="l00017"></a>00017 
<a name="l00018"></a>00018 <span class="comment">/* </span>
<a name="l00019"></a>00019 <span class="comment">  BASIC INTERRUPT DRIVEN DRIVER FOR MAKE BOARD. </span>
<a name="l00020"></a>00020 <span class="comment">*/</span>
<a name="l00021"></a>00021 
<a name="l00022"></a>00022 <span class="comment">/* Scheduler includes. */</span>
<a name="l00023"></a>00023 
<a name="l00024"></a>00024 <span class="preprocessor">#include "FreeRTOS.h"</span>
<a name="l00025"></a>00025 <span class="preprocessor">#include "types.h"</span>
<a name="l00026"></a>00026 <span class="preprocessor">#include "fasttimer.h"</span>
<a name="l00027"></a>00027 <span class="preprocessor">#include "fasttimer_internal.h"</span>
<a name="l00028"></a>00028 <span class="preprocessor">#include "AT91SAM7X256.h"</span>
<a name="l00029"></a>00029 
<a name="l00030"></a>00030 <span class="keywordtype">void</span> DisableFIQFromThumb( <span class="keywordtype">void</span> )
<a name="l00031"></a>00031 {
<a name="l00032"></a>00032   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"STMDB SP!, {R0}"</span> );   <span class="comment">/* Push R0.                 */</span>
<a name="l00033"></a>00033   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"MRS   R0, CPSR"</span> );    <span class="comment">/* Get CPSR.                */</span>
<a name="l00034"></a>00034   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"ORR   R0, R0, #0x40"</span> ); <span class="comment">/* Disable FIQ.           */</span>
<a name="l00035"></a>00035   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"MSR   CPSR, R0"</span> );    <span class="comment">/* Write back modified value.       */</span>
<a name="l00036"></a>00036   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"LDMIA SP!, {R0}"</span> );   <span class="comment">/* Pop R0.                  */</span>
<a name="l00037"></a>00037   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"BX    R14"</span> );       <span class="comment">/* Return back to thumb.          */</span>
<a name="l00038"></a>00038 }
<a name="l00039"></a>00039     
<a name="l00040"></a>00040 <span class="keywordtype">void</span> EnableFIQFromThumb( <span class="keywordtype">void</span> )
<a name="l00041"></a>00041 {
<a name="l00042"></a>00042   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"STMDB SP!, {R0}"</span> );   <span class="comment">/* Push R0.                 */</span>  
<a name="l00043"></a>00043   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"MRS   R0, CPSR"</span> );    <span class="comment">/* Get CPSR.                */</span>  
<a name="l00044"></a>00044   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"BIC   R0, R0, #0x40"</span> ); <span class="comment">/* Enable FIQ.              */</span>  
<a name="l00045"></a>00045   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"MSR   CPSR, R0"</span> );    <span class="comment">/* Write back modified value.       */</span>  
<a name="l00046"></a>00046   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"LDMIA SP!, {R0}"</span> );   <span class="comment">/* Pop R0.                  */</span>
<a name="l00047"></a>00047   <span class="keyword">asm</span> <span class="keyword">volatile</span> ( <span class="stringliteral">"BX    R14"</span> );       <span class="comment">/* Return back to thumb.          */</span>
<a name="l00048"></a>00048 }
<a name="l00049"></a>00049 
<a name="l00050"></a>00050 <span class="keyword">extern</span> <span class="keyword">struct </span>FastTimer_ FastTimer;
<a name="l00051"></a>00051 
<a name="l00052"></a>00052 <span class="comment">// At the moment, the FastTimer ISR or callbacks, very importantly, can't call any OS stuff since</span>
<a name="l00053"></a>00053 <span class="comment">// the IRQ might happen any old where</span>
<a name="l00054"></a>00054 
<a name="l00055"></a>00055 <span class="keywordtype">void</span> FastTimer_Isr( <span class="keywordtype">void</span> ) __attribute__ ((naked));
<a name="l00056"></a>00056 
<a name="l00057"></a>00057 <span class="comment">// Made non-local for debugging</span>
<a name="l00058"></a>00058 FastTimerEntry* te;
<a name="l00059"></a>00059 <span class="keywordtype">int</span> jitter;
<a name="l00060"></a>00060 <span class="keywordtype">int</span> timeReference;
<a name="l00061"></a>00061 
<a name="l00062"></a>00062 <span class="keywordtype">void</span> FastTimer_Isr( <span class="keywordtype">void</span> )
<a name="l00063"></a>00063 {
<a name="l00064"></a>00064   portENTER_FIQ( );
<a name="l00065"></a>00065   <span class="keywordtype">int</span> status = AT91C_BASE_TC2-&gt;TC_SR;
<a name="l00066"></a>00066   <span class="keywordflow">if</span> ( status &amp; AT91C_TC_CPCS )
<a name="l00067"></a>00067   {
<a name="l00068"></a>00068     FastTimer.servicing = <span class="keyword">true</span>;
<a name="l00069"></a>00069 
<a name="l00070"></a>00070     <span class="comment">//AT91C_BASE_TC2-&gt;TC_CCR = AT91C_TC_CLKDIS;</span>
<a name="l00071"></a>00071 
<a name="l00072"></a>00072     <span class="comment">// make sure there's not another IRQ while we're processing</span>
<a name="l00073"></a>00073     timeReference = AT91C_BASE_TC2-&gt;TC_RC;
<a name="l00074"></a>00074     AT91C_BASE_TC2-&gt;TC_RC = 0xFF00;
<a name="l00075"></a>00075 
<a name="l00076"></a>00076 <span class="preprocessor">#ifdef FASTIRQ_MONITOR_IO</span>
<a name="l00077"></a>00077 <span class="preprocessor"></span>    Io_SetTrue( FASTIRQ_MONITOR_IO );
<a name="l00078"></a>00078 <span class="preprocessor">#endif</span>
<a name="l00079"></a>00079 <span class="preprocessor"></span>
<a name="l00080"></a>00080 <span class="preprocessor">#ifdef FASTIRQ_STATS</span>
<a name="l00081"></a>00081 <span class="preprocessor"></span>    <span class="keywordtype">int</span> startCount = AT91C_BASE_TC2-&gt;TC_CV;
<a name="l00082"></a>00082 
<a name="l00083"></a>00083     <span class="comment">// moved outside for debugging</span>
<a name="l00084"></a>00084     <span class="comment">//int jitter;</span>
<a name="l00085"></a>00085     jitter = AT91C_BASE_TC2-&gt;TC_CV;
<a name="l00086"></a>00086 
<a name="l00087"></a>00087     <span class="keywordflow">if</span> ( ++FastTimer.count == 1000 )
<a name="l00088"></a>00088     {
<a name="l00089"></a>00089       <span class="comment">// need to not do division here... takes too long</span>
<a name="l00090"></a>00090       <span class="comment">//FastTimer.jitterTotal = FastTimer.jitterTotal / FastTimer.count;</span>
<a name="l00091"></a>00091       FastTimer.jitterTotal = 0;
<a name="l00092"></a>00092       FastTimer.jitterMax = 0;
<a name="l00093"></a>00093       <span class="comment">// need to not do division here... takes too long</span>
<a name="l00094"></a>00094       <span class="comment">// FastTimer.durationTotal = FastTimer.durationTotal / FastTimer.count;</span>
<a name="l00095"></a>00095       FastTimer.durationTotal = 0;
<a name="l00096"></a>00096       FastTimer.durationMax = 0;
<a name="l00097"></a>00097       FastTimer.count = 1;
<a name="l00098"></a>00098     }
<a name="l00099"></a>00099     
<a name="l00100"></a>00100     FastTimer.jitterTotal += jitter;
<a name="l00101"></a>00101         
<a name="l00102"></a>00102     <span class="keywordflow">if</span> ( jitter &gt; FastTimer.jitterMax )
<a name="l00103"></a>00103       FastTimer.jitterMax = jitter;
<a name="l00104"></a>00104     <span class="keywordflow">if</span> ( jitter &gt; FastTimer.jitterMaxAllDay )
<a name="l00105"></a>00105       FastTimer.jitterMaxAllDay = jitter;
<a name="l00106"></a>00106 
<a name="l00107"></a>00107 <span class="preprocessor">#endif</span>
<a name="l00108"></a>00108 <span class="preprocessor"></span>
<a name="l00109"></a>00109     <span class="comment">//FastTimerEntry* te = FastTimer.first;</span>
<a name="l00110"></a>00110     <span class="comment">// Use this during debuggin</span>
<a name="l00111"></a>00111     te = FastTimer.first;
<a name="l00112"></a>00112 
<a name="l00113"></a>00113     FastTimer.next = NULL;
<a name="l00114"></a>00114     FastTimer.previous = NULL;
<a name="l00115"></a>00115     FastTimer.nextTime = 0xFF00;
<a name="l00116"></a>00116     <span class="keywordtype">int</span> removed = <span class="keyword">false</span>;
<a name="l00117"></a>00117     <span class="comment">// timeReference = AT91C_BASE_TC2-&gt;TC_CV;</span>
<a name="l00118"></a>00118 
<a name="l00119"></a>00119     <span class="keywordflow">while</span> ( te != NULL )
<a name="l00120"></a>00120     {
<a name="l00121"></a>00121       FastTimer.next = te-&gt;next;
<a name="l00122"></a>00122       te-&gt;timeCurrent -= ( timeReference + AT91C_BASE_TC2-&gt;TC_CV );
<a name="l00123"></a>00123       <span class="keywordflow">if</span> ( te-&gt;timeCurrent &lt;= FASTTIMER_MINCOUNT )
<a name="l00124"></a>00124       {
<a name="l00125"></a>00125         <span class="comment">// Watch out for gross errors</span>
<a name="l00126"></a>00126         <span class="comment">//if ( te-&gt;timeCurrent &lt; -FASTTIMER_MINCOUNT)</span>
<a name="l00127"></a>00127         <span class="comment">//  te-&gt;timeCurrent = -FASTTIMER_MINCOUNT;</span>
<a name="l00128"></a>00128 
<a name="l00129"></a>00129         <span class="keywordflow">if</span> ( te-&gt;repeat )
<a name="l00130"></a>00130         {
<a name="l00131"></a>00131           te-&gt;timeCurrent += te-&gt;timeInitial;
<a name="l00132"></a>00132         }
<a name="l00133"></a>00133         <span class="keywordflow">else</span>
<a name="l00134"></a>00134         {
<a name="l00135"></a>00135           <span class="comment">// remove it if necessary (do this first!)</span>
<a name="l00136"></a>00136           <span class="keywordflow">if</span> ( FastTimer.previous == NULL )
<a name="l00137"></a>00137             FastTimer.first = FastTimer.next;
<a name="l00138"></a>00138           <span class="keywordflow">else</span>
<a name="l00139"></a>00139             FastTimer.previous-&gt;next = FastTimer.next;  
<a name="l00140"></a>00140           removed = <span class="keyword">true</span>;
<a name="l00141"></a>00141         }
<a name="l00142"></a>00142 
<a name="l00143"></a>00143         <span class="keywordflow">if</span> ( te-&gt;callback != NULL )
<a name="l00144"></a>00144         {
<a name="l00145"></a>00145           <span class="comment">// in this callback, the callee is free to add and remove any members of this list</span>
<a name="l00146"></a>00146           <span class="comment">// which might effect the first, next and previous pointers</span>
<a name="l00147"></a>00147           <span class="comment">// so don't assume any of those local variables are good anymore</span>
<a name="l00148"></a>00148           (*te-&gt;callback)( te-&gt;id );
<a name="l00149"></a>00149         }
<a name="l00150"></a>00150       }
<a name="l00151"></a>00151       
<a name="l00152"></a>00152       <span class="comment">// note that this has to be better than this ultimately - since</span>
<a name="l00153"></a>00153       <span class="comment">// the callback routine can remove the entry without letting us know</span>
<a name="l00154"></a>00154       <span class="comment">// at all.</span>
<a name="l00155"></a>00155       <span class="keywordflow">if</span> ( !removed )
<a name="l00156"></a>00156       {
<a name="l00157"></a>00157         <span class="keywordflow">if</span> ( FastTimer.nextTime == -1 || te-&gt;timeCurrent &lt; FastTimer.nextTime )
<a name="l00158"></a>00158         {
<a name="l00159"></a>00159           FastTimer.nextTime = te-&gt;timeCurrent;
<a name="l00160"></a>00160         }
<a name="l00161"></a>00161         FastTimer.previous = te;
<a name="l00162"></a>00162       }
<a name="l00163"></a>00163 
<a name="l00164"></a>00164       te = FastTimer.next;
<a name="l00165"></a>00165     }
<a name="l00166"></a>00166 
<a name="l00167"></a>00167     <span class="keywordflow">if</span> ( FastTimer.first != NULL )
<a name="l00168"></a>00168     {
<a name="l00169"></a>00169       <span class="comment">// Make sure it's not too big</span>
<a name="l00170"></a>00170       <span class="keywordflow">if</span> ( FastTimer.nextTime &gt; 0xFF00 )
<a name="l00171"></a>00171         FastTimer.nextTime = 0xFF00;
<a name="l00172"></a>00172       <span class="comment">// Make sure it's not too small</span>
<a name="l00173"></a>00173       <span class="keywordflow">if</span> ( FastTimer.nextTime &lt; AT91C_BASE_TC2-&gt;TC_CV + 20 )
<a name="l00174"></a>00174         FastTimer.nextTime = AT91C_BASE_TC2-&gt;TC_CV + 20;
<a name="l00175"></a>00175       AT91C_BASE_TC2-&gt;TC_RC = FastTimer.nextTime;
<a name="l00176"></a>00176     }
<a name="l00177"></a>00177     <span class="keywordflow">else</span>
<a name="l00178"></a>00178     {
<a name="l00179"></a>00179       AT91C_BASE_TC2-&gt;TC_CCR = AT91C_TC_CLKDIS;
<a name="l00180"></a>00180       FastTimer.running = <span class="keyword">false</span>;
<a name="l00181"></a>00181     }
<a name="l00182"></a>00182 
<a name="l00183"></a>00183 <span class="preprocessor">#ifdef FASTIRQ_STATS    </span>
<a name="l00184"></a>00184 <span class="preprocessor"></span>    <span class="keywordtype">int</span> duration = AT91C_BASE_TC2-&gt;TC_CV - startCount;
<a name="l00185"></a>00185     FastTimer.durationTotal += duration;  
<a name="l00186"></a>00186     <span class="keywordflow">if</span> ( duration &gt; FastTimer.durationMax )
<a name="l00187"></a>00187       FastTimer.durationMax = duration;
<a name="l00188"></a>00188     <span class="keywordflow">if</span> ( duration &gt; FastTimer.durationMaxAllDay )
<a name="l00189"></a>00189       FastTimer.durationMaxAllDay = duration;
<a name="l00190"></a>00190 <span class="preprocessor">#endif</span>
<a name="l00191"></a>00191 <span class="preprocessor"></span>
<a name="l00192"></a>00192 <span class="preprocessor">#ifdef FASTIRQ_MONITOR_IO    </span>
<a name="l00193"></a>00193 <span class="preprocessor"></span>    Io_SetFalse( FASTIRQ_MONITOR_IO );
<a name="l00194"></a>00194 <span class="preprocessor">#endif</span>
<a name="l00195"></a>00195 <span class="preprocessor"></span>
<a name="l00196"></a>00196     <span class="comment">// AT91C_BASE_TC2-&gt;TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;</span>
<a name="l00197"></a>00197     FastTimer.servicing = <span class="keyword">false</span>;
<a name="l00198"></a>00198   }
<a name="l00199"></a>00199   portEXIT_FIQ( );
<a name="l00200"></a>00200 }
<a name="l00201"></a>00201 
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  <p class="footer">The Make Controller Kit is an open source project maintained by <a href="http://www.makingthings.com">MakingThings</a>.<br />
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		This document was last updated on 5 Dec 2007.
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